Sealant film, laminated film, and packaging material

Abstract

A sealant film including a surface resin layer (A), an adhesive resin layer (B), a release resin layer (C), and a heat seal resin layer (D) that are laminated is provided. The adhesive resin layer (B) contains a thermoplastic elastomer (b1) and a tackifier resin (b2). The release resin layer (C) contains a certain amount of an ethylene ionomer (c1) with a polar group concentration exceeding 5.5 mol % and an ethylene ionomer (c2) with a polar group concentration of 5.5 mol % or less in a resin component contained in the release resin layer (C). The heat seal resin layer (D) contains a certain amount of an olefin resin (d1) and a thermoplastic elastomer (d2) in a resin component contained in the heat seal resin layer (D).

1 . A sealant film comprising:
 a surface resin layer (A),   an adhesive resin layer (B),   a release resin layer (C), and   a heat seal resin layer (D),   wherein:   the surface resin layer (A), the adhesive resin layer (B), the release resin layer (C), and the heat seal resin layer (D) are laminated,   the adhesive resin layer (B) contains a thermoplastic elastomer (b1) and a tackifier resin (b2),   the release resin layer (C) contains 40% by mass or more of an ethylene ionomer (c1) with a polar group concentration exceeding 5.5 mol % in a resin component contained in the release resin layer (C),   the release resin layer (C) further contains 0 to 60% by mass of an ethylene ionomer (c2) with a polar group concentration of 5.5 mol % or less in the resin component contained in the release resin layer (C),   the heat seal resin layer (D) contains an olefin resin (d1),   the heat seal resin layer (D) contains 0 to 80% by mass of a thermoplastic elastomer (d2) in a resin component contained in the heat seal resin layer (D), and   a percentage of the ethylene ionomer (c2) and the thermoplastic elastomer (d2) as expressed by the following formula is 20 to 60%:
   [(( Wc 2/ Wct )×100)+(( Wd 2/ Wdt )×100)]/2
 
   where   Wct is a total amount by mass of the resin component contained in the release resin layer (C),   Wc2 is an amount by mass of the ethylene ionomer (c2) in the resin component contained in the release resin layer (C),   Wdt is a total amount by mass of the resin component contained in the heat seal resin layer (D), and   Wd2 is an amount by mass of the thermoplastic elastomer (d2) in the resin component contained in the heat seal resin layer (D).   
     
     
         2 . The sealant film according to  claim 1 , wherein the thermoplastic elastomer (b1) contained in the adhesive resin layer (B) is at least one selected from styrene elastomers, ethylene elastomers, and propylene elastomers. 
     
     
         3 . The sealant film according to  claim 1 , wherein the olefin resin (d1) contained in the heat seal resin layer (D) is a propylene resin. 
     
     
         4 . The sealant film according to  claim 1 , wherein the surface resin layer (A) is a resin layer containing an olefin resin as a main resin component. 
     
     
         5 . The sealant film according to  claim 1 , wherein the sealant film is resealable after peeled at an interface between the adhesive resin layer (B) and the release resin layer (C). 
     
     
         6 . The sealant film according to  claim 1 , wherein a seal strength after resealing that is measured after the sealant film is heat-sealed and then peeled, pressure-bonded again at 23° C. and 0.2 MPa for a sealing time of 1 second, and then left for 5 minutes at 23° C. and 50% RH is 2 N/15 mm or more. 
     
     
         7 . The sealant film according to  claim 1 , wherein the sealant film has a total thickness of 10 to 100 μm. 
     
     
         8 . A laminate film comprising the sealant film according to  claim 1 . 
     
     
         9 . A packaging material comprising the sealant film according to  claim 1 . 
     
     
         10 . A container comprising:
 an opening mainly composed of a propylene resin; and   the packaging material according to  claim 9  heat-sealed at the opening of the container.